Magnetic movement



April 17, 1934- c. MESSICK 1,955,248

MAGNETIC MOVEMENT Filed April 18, 1928 2 Sheets-Sheet 1 INVENTOR FIGS21.

2 Sheets-Sheet 2 INVENTOR Patented Apr. 17, 1934 UNITED STATES PATENTOFFICIE 3 Claims.

One object of this invention is to provide an improved electromagneticmovement in place of solenoids, direct approach magnets shearingmagnets, moving coils and magnetic movements of various reciprocatingtypes.

Another object is to provide an improved electromagnetic movement fortelephone receivers, loud speakers, transmitters, microphones,phonograph pick ups, etc.

Another object is to combine such a movement with a radially tensioneddiaphragm of large size and suitable for operation without the aid of ahorn.

The invention consists in the improved design of one or more of theparts and combinations of one or more of the parts which will appearfrom the following detail descriptions of embodiments of the invention,and will be pointed out in the appended claims.

Referring to the accompanying drawings:,-

Fig. 1 is a diagrammatic cross section of one of my magnetic movementsprovided with a field excited by a direct current winding.

Fig. 2 is a diagrammatic cross section of a modi- Lo fled form of mymagnetic movement provided with a direct current field excited by meansof a disc shaped permanent magnet.

Fig. 3 is a diagrammatic cross section of a modified form of poles formy magnetic movement as applied to a radially tensioned diaphragm. Fig.3a is a perspective of the armature of Fig. 3.

Fig. 4 is a diagrammatic cross section of a modified form of my magneticmovement com- ;5 bined with a radially tensioned diaphragm.

Fig. 5 is an exploded view of a modified form of one of the poles of mymagnetic movement.

Fig. 6 is a plan view of a fragment of the device shown in Fig. 4.

. In Fig. 1 the numeral 1 indicates a vibratory diaphragm, designed toreciprocate up and down in a conventional manner, upon which is secureda support ring of nonmagnetic material 2, carrying a ring shapedarmature 3, of magnetic ma- 43 terial, preferably discontinuous in itscircumference. This discontinuity may be effected by radially slottingthe armature 3 or making it of magnetic particles embedded in a matrixof for instance hard rubber or a hard resin, or laminations, preferablyradial, may be used.

The principal object of such magnetic discontinuity of armature 3, is toprevent radial unbalance of the magnetic pull due to accidentaleccentric mounting of armature 3. A direct current field is induced inthe annular pole 4, yoke 5,

and central pole 6 through armature 3 by the conventional direct currentwinding 7. Such magnetic discontinuity of armature 3 will also tend toprevent induced or eddy currents in armature 3. Voice coils 8 and 9 aredesigned to actuate the armature 3 and drive diaphragm l as a telephonereceiver diaphragm or when my mag netic movement is used as atransmitter alternating current is induced in voice coils 8 and 9. Thevoice coils 8 and 9 should preferably be so connected that their actionwill be cumulative to either increase the fiow of magnetic fiux in thepole pieces above them and simultaneously to decrease the flow ofmagnetic flux in the pole pieces below them, or the reverse. Thearmature 3 will thus be pulled up or down according to the momentarydirection of fiow of the voice 0011 current.

It should be noted that the armature 3, support ring 2 and diaphragm 1should be made as light as possible consistent with the performance oftheir respective functions, preferably much lighter than it is practicalto clearly show same in Fig. l. A similar remark applies to the movingparts in all the other figures of the drawings.

It should be also noted that the armature 3 overlaps the adjacentpole-pieces less than half. when the armature is in its indicated normalposition.

The modification shown in Fig. 2 is provided with a diaphragm 11, havinga copper ring-shaped support 12, carrying an armature 13. An annularpole 14 forms the central part of an iron frame casting 140 which isalso provided with a ringshaped projection 15, upon which is secured byscrews 16 a radially magnetized, permanent disk magnet 17.

At the centre of magnet 17 is secured one-half of a pole 18, the otherhalf thereof consisting of the iron mushroom 18. Both casting 140 andmagnet 17 are perforated with holes, respectively, bearing the numerals19 and 20, which holes are designed to prevent compression of airbetween diaphragm 11 and casting 140 when diaphragm 11 vibrates.

A heavy copper ring 21 is positioned between the lower enlarged portion22 of half pole l8 and pole 14. Both copper ring 21 and copper ring 12are designed to reduce leakage of alternating current fiux' from a voicecoil 23, when my magnetic movement is operated as a motor or into voicecoil 23 when operated as a generator, as the case may be.

In the construction of Fig. 2 only one voice coil, namely 23, is usedand it is secured in place by being mounted upon mushroom 180 which isheld in position with respect to the magnet 17 and half pole 18 by screw24. Member 22 and copper ring 21 are secured to pole 14 by screws 25-25.

It will be noted that the shape of the voice coils 8, 9 and 23 differ,but each is embedded in the adjacent pole. This is to increase theefiiciency of my magnetic movement. Such increase of efficiency may inome cases be further augmented by making the poles and the armature ofspecial magnetic alloys of high magnetic permeability. The exact shapeof the armature and the poles to fit a particular set of conditions maybe largely predetermined by the use of conventional electrical formulas.

The modification shown in Fig. 3 indicates a radially tensioneddiaphragm 31, and specially shaped poles consisting of an annular pole32 and a central pole 33, these poles being provided with voice coilsStand 35 respectively. The diaphragm 31 may be of, for instan e, thesame general type as that shown in Fig. 6 hereof. The

special shape of poles 32 and 33 is designed to permit the use withoutexcessive magnetic leakage, of a specially light weight armature 36, inwhich all of the magnetic material is used to advantage. T-e armature 35is soldered to a brass ring 37, which is soldered to filaments 38, ofdiaphragm where the filaments 38 lie in a common horizontal plane, thusfacilitating the soldering.

In Figs. 4 and 6 a perforated iron frame casting 41 is shown supportinga radially tensioned diaphragm 42, which is tensioned thereon at therivets 43 of casting 11. The radial tension members consist of thefilaments 44, upon which is cemented a surface member 45, shown in Fig.6. Reference. is invited to my U. 5. Patents Nos. 1,503,696 and1,545,119, which show radially tensioned diaphragnis and describe thecharacteristics of such diaphragins.

At the centre of Fig. 4 is shown a double cup i 17 to contain the voicecoil 48. The double cup i "e7 is preferably made of silicon steel orsome magnet alloy of high permeability, and is held in casting 41 bybeing tightly fitted thereinto. A flanged brass tube 19 is fastened byscrews 50-50 to casting 11, and contains a centre pole 51 which issilver soldered into tube 49.

Pole 51 is surrounded at its upper end by armature 52.

Armature 52 is silver soldered to the lower end of a hollow brassferrule 53, made of very thin gauge brass. Ferrule 58 is provided withholes 530 to prevent air pressure building up therein during vibration,and a flange 54, acts as a spacer to separate the upper from the lowerfilaments of diaphragm 12. The filaments 44-, which are preferably madeof music spring wire are brought into a common plane by the lacingmember 55. A larger number of filaments 4 1, is preferable to thatdiagrammatically indicated in Fig. 6.

Two 6 magnets 5557 provide direct current flux, and each has the samepolarity where secured to frame 41 by tap screws 5858 and the oppositepolarity where secured to the centre pole 51 by the tap screw 59. Braces60 and 61 are also secured to the magnets 56 and 5'7, and the centerpole 51 by screw 59, and the ends of braces 6051 are secured at theirouter ends to casting 41 by screws 62.

Fig. 5 shows a modified form of the double cup 4647 of Fig. i. The formshown in Fig. 5 is split radially and the two identical parts thereofare indicated by the numerals 63 and 64.

I do not limit myself to the exact construction above described, and themagnetic elements, particularly the poles and the armature may bedesigned in accordance with magnetic theory to give such performancechar cteristics as are required for any form of magnetic movement wherethe work must be moved in other than an endless orbit.

I claim:-

1. In a driving motor for phragrns, a central pole piece and asurrounding pole piece, each of said pole pieces having two pole faces,an annular coil between the pole faces of each pole piece, m ans forcreating a normal magnetic field between said pole pieces, means forenerg rig said coil with a control current for disturbing the normalmagnetic field, and an annular armature made of magnetic materialpositioned in the air gap between said pole pieces and adapted to moveparallel to said pole faces and having a length not greater than thedistance be tween the centers of said pole faces.

2. A loud speaker motor comprising a field magnet structure having acentral pole piece and a second pole piece encircling the central polepiece and forming with it an annular air gap, at least one of said polepieces having two pole faces, an annular armature made of magneticmaterial reciprocable in said gap in a path parallel with said polefaces, the armature and said pole faces being so proportioned withrespect to each other that when the armature is in its normal position lthan half of each of pole faces is covered yum loud speaker diaby thearmature, and a coil associated with one of the parts of the motor toeffect reciprocation of the armature when the coil is energized withvarying current.

3. A loud speaker motor comprising a field magnet, having a first polepiece and a second pole piece adjacent to the first pole piece andforming with it an air gap, at least one of said pole pieces having twopole faces, an armature made of magnetic material reciprocable in saidap in a path substantially parallel with said 1 pole faces, elasticsuspension means designed to wholly support said armature, said armatureand said pole faces being so proportioned with respect to each otherthat when th armature is in its normal position less than half of thetotal area of said two pole faces is covered by the armature, and astationary coil associated with thepole pieces to effect reciprocationof the armature when the coil is energized with varying current. CHARLESMESSICK.

